This study examines the level of microbiological contamination of household waste water. Microbiological analyzes of 10 samples of waste household water from different locations. The samples with the presence of aerobic mesophilic bacteria; Enterobacteriaceae, Escherichia coli, the presence of yeast, mold presence, the presence of Staphylococcus aureus and Clostridium bacteria. After a certain presence and the number of individual microorganisms, samples were treated with the preparation of effective microorganisms (EM AKTIV). After seven days, the presence of certain
microorganisms of the same as in the original sample. The results are compared and graphically presented.